Extensometer



F. F. METZGER. EXTENSOMET ER. APPLICATION FILED JUNE 25 1917.

' Patented June 28, 1921.

2 SHEETS-SHEET I.

Ferdinand fiM et zye r gflwmt 5m F. F. METZGER.

exremsomma.

v APPLICATION F|LED JUNE25, [917- 1,382,663, Patented June 28, 1921.

2 SHEETS-SHEET 2.

Ferdimlmbl". Metzyer To all whom zit-may concern:

- the specimen vary more thanother surfaces ATFS AT.E T, ol FlCE-- lrnnpmann r. METZ ER; or rnrL n Lrnr rENnsYLvANIAf- EXTENSOIEETER.

. Be it known that I, FERDINAND F. Mn'r'z- GER, a citizen ofthe United States, residing at Philadelphia, in the county of Philadelphia and State. of Pennsylvania, have invented certain new and useful Improvements in Extensometers, of which the followingis a specification.

My invention relates to improvements in extensometers which are used for measuring: the amount of variation in a body of material when placed'under stress. The usual method of using the instrument is to place it upon a specimen made from the material to be tested. The specimen is placed in a testing machine in which the specimen is placed under strain and the amount of deformation of the specimen is indicated upon an indicating instrument. 1

It has been found that certain surfaces of of the same specimen. Thus-the surface of one side. of the specimen may vary more than the opposite surface and a true average measurement of the deformation of the specimen could not be obtained.

The object of my invention is to provide means for obtaining the average of the def ormation in the surface of the material which is being tested. In carrying out this feature of myinvention I- employ a clamping collar having two or more'points of contact to rigidly hold the same upon the specimen, so that the'cla'mping collar will tilt or oscillate, due to the uneven surface deformation of the specimen. The said clamping collar is'mounted in a universal joint, known as a gimbal joint, so that the center of oscillation will be found by the gimbal joint and the average deformation of the specimen'will be communicated to the indicating instrument from which the readings are taken; a' further object of my invention is to construct-the clamping member or gimbal joint with an opening formed in one'side thereof so that it can be placed upon the specimen after the ends of the latter are ecured in the testing machine; a still further object of my invention is to provide a stop to limit the movement of the movable to the micrometer if the specimen should break and a sudden strain put upon the said arm; and a still further object of my invention is to-provide a retaining plate for enx gaging all the parts-of the gimbal joint, 'or

Specification of Letters Patentf Patented fin Application filed June 25, 1917. Serial No. 176,678.

clamping member, and hold them in parallel alinement when the extensometer is be- 111 attached to the specimen. a l

n the accompanying drawings in which like reference characters refer to like parts;

Figure 1, is a front elevation of my improvedex tensometer; Fig.2, is a side elevation of. 'Fig. 1; F g. 3, 1s a transverse vertical sec tlon on line 3-3 Fig. 2; Fig. 4,"isa trans verse vertical section onfline l- 1 Fig. 2;

Fig. 5 is a vertical longitudinal section on line..55 Fig. 1; and Fig. 6, is a longitudi-- nal section of a modified formofmy invention;

Referring to the drawings, 1 and 2 are the clamplng members adapted to be held upon the specimen 3 which is to be tested, as-

shown in Fig. 5. The clamping members 1 and 2 each consist of the innerclamping collar 5, provided with pins or screws 6, 7 and 8,v having conical points formed-thereon,

which engagethe specimen 3 and hold theclamping collar 5. The screw 6 is provided with a large head so that it may be operated by the fingers. The-clamping collar- 5 is pivotally mounted in an intermediate bearing member 9 by the pivot pinsor stud shafts 12 and 13 arranged diametrically opposite to eachother to permit the clamping collar 5 to have a free oscillatory movement, upon the studs o'rpins12 and 13.

The intermediate bearing member 9 is piv-. otally mounted in a yoke 15 by pins 16 and '17, arranged diametrically opposite to each other and also located at right angles to the said pivot pins 12 and 13, which pivotally connect the intermediate bearing member 9 with the clamping collar 5i It willbe seen that the clamping collar is so mounted in the yoke 15, that it is free to oscillate in any direction, within certain limits The'clamping collar 5 and the-intermediate bearing member 9 are each made in the form of segments thus forming openings in the sides of the clamping members for the free passage of the specimen 3. By this arrangement the extensometer'may beattached to the specimen after the latter is secured in the testlng machine.

- When the eXtensometer-is not in'use, oris being placed upon thespecimen, it is' nec'e s sary that the several parts of the clamping members 1 and 2, should be held in parallel alinement; this accomplished by a check plate 19 looselymou'nted'u'pon pins-0r screws 20 and 21, which latter enter and arecarried by the intermediate bearing member. 9. Springs 22 are provided upon the screws 20 and 21, and exert sufficient ressure againstthe cheek plate 19 to retain all the, parts against which it contacts in the same verticalplane. The cheek plates 19 are each formed as-"shcwn *in"'F-igs. '2'- and 4,'"with' an opening provided thereinto permit :the-speclmen to be freely admitted atthe side of the extensometer. I

The form oi: ex-tensometer,: shown in= Figs.

1 to 5, inclusive shows the:clampring"mem- Ibers Land 2 mounted in the: frame 24, consisting of the: side; plates 25 and: 26v'secured together by the cross-pieces 2!- and 28. {Dhe yoke 15 of :the clamping member 2 is. rigidly secured between theside plates25-and 26'yofi =the -i-rame,ias shown in Figs-4 and- '5- Ther'yoke 15 ofthe clamping member 1-,- is integrally formed; with the arm 30, which is provided with pins 31 1 and 2 32 upon which.

theaarmis :pivoted in the notches 33 formed in the side plates of the frame 24. A spring 35 is secured to 1 the cross piece 28' of the frame and saidf spring -35. sis: provided'qwith: avms' 36 which bear aginst thewpivot-pins 31 and 32=and: retain the'latter in thelnotches 9 33 v formed :in the: frame 24, when: the 4 arm; 30

is acting under-normal conditions.

The-movement of-theiarm 130 is limited by anhac lj'usta-ble stop 37 (see- Fig; 5,) secured ma fixed:-position in the cross-piecei 28.

When'e'the arm 30 reaches the limit ofits movement-it strikes the stop37, the spring.

36 =wi ll yield:andiallow the pivot pins*81 and- 32'on theqarm 301 to slip out of the notches 33 in the frame 24, and thus-release the arm 30. :"I hestop feature is iprovidedfor the 'purpose' of throwingthe-arm'30 out of its fulcrum if the specimen whichfis being testedshould break; in whichv case the stop 37 prevents-.lthe arm "30' from exerting w an nun- :sual pressure-against the micrometer-40, which would have an injurious 1' effect upon the same.

. The1arm=30,1as shown in: Fig. 5, actsupon a lever" 42 pivoted in the frame 24, which lever 42,1in '-turn, acts upon the stem 41. of the the i bodied in an extensometer having a U Shaped spring meunber 50, which takes-the place of thefframe 24"above described. The clamping members 1 and are secured to the free ends of the arms of the U-shaped member 50.

The' pivoted arm 55 embraces the U-shaped member 50and the cross-bar 56 of the arm 55 is pivoted between the brackets 51 and 52, carried by the U-shaped member.50.. The

free 'end'of the arm 55 acts upon- 'the stem 41: ofthemicrometerAD. A stop 58, in the form of a screw is provided upon one portion of the U-shaped:;member- 50, fork the'l purpose. at throwing the s55xiout of the pivot} points. :inthe abracketsi51 :xa-n'd" 52, in: case 4 an unusual: strain .tis. exerted ,npon the arm '55,, 1and'; thus {preventing the? arm::55 1' frominjuringthe micrometer.

icalapointed: screws 6,: Ziand' 810i! theuclampingcollar '5 ,--when the specimensiszput understrain, one w; surface Y of i the specimen. im'ayi site surface, ithus: tending to tilt the clampingcollan -5 OlltiOf its perpendicular position in 'relation to the.

stretch more than the :op

oting the inner clamping collarfiin'theyoke 15, the: averag amount of oscillation 'Willvbe transferred to the pivoted:- armpand thus-thereadings upon the .indicatorx williigivervthe mean expansion of the entire specimen between :polnts.

19 a will not interfere-wwithz. the operation pf the gimbal oint, was: :the-springs'r 221-:which press against the-plate 19I-have only-sufficient strength to hold inalinementthe partsvof the-'gimbal joint,

'lhe clamping collar. can: lie-provided with two -or' more clamp screwsi'or any other a In my improved: clamping-members 1 and: 2 the specimen is clamped-between theucon-i a It will be' understood: :that the oheekiplate clamping-means:iorvsecuringaithe specimen 1 therein, without-departing from rmy in vention, a

Having 1 :thus described =mv: invention '1 claim and: desire to secure'by: EettersvB atient '1-.- -A device ofmthe character udescribd comprising, twoeigimbal ijoints r-comprising clamping means, "-a'= member carryin'gmthe gimbaljointsv 'in whichithe: latter-2 wrea yield:-

ingly mounted in relation to each otherpand means-actuated: byntheagimbal: joints ion-indicating the "variation-i in the: (distance: be". tween the .gimbalr'tj'oint'sp 2. In a device for measuringJthe-ideformat-. tion 0fv an specimen, clamping members: each pivotallyconnected together,ipivotspinsapivotally connecting.thermembersi oithel'gimbal joints 5 together, 1 said pivot-Jpins extending radially" a commom center, and means for attaching: the clamping-members to ithe specimen. 7 A V 3.- In adevicei of the: character: idescnibed,

means upon: thewoo'llari ifor securingsit toria specimen, a" bearinprmemben'embracingtlie collar and 'pivota 1y iconn'ectedf thereto; 1a

yoke embracing the bearing member and pivotally connected thereto, a second clamping member secured to the specimen, and means operated by the said yoke for indieating the average oscillating movement of the specimen between the said clamping members.

4. In a device for measuring the deformation of a specimen, a clamping member comprising a collar, means upon the collar for securing it to a specimen, a bearing member embracing the collar, pivot pins for pivotally connecting the bearing member with the collar, a yoke embracing the bearing member, pivot pins for pivotally connecting the bearing member with the yoke, said last mentioned pivot pins being located at approximately right angles with the axis on which the said collar and said bearing member are connected together and means operated .by the yoke for indicating the movement of the clamping member.

5. In a device for measuring the deformation of a specimen, a collar, means for rigidly securing the collar to the specimen, a bearing member embracing the collar and ivotally connected thereto, a member emracing the bearing member and pivotally connected thereto, and indicating means actuated by the last mentioned member carryingI the bearing member and the collar.

6. n a device of the character described, a collar, clamping devices in the collar, one

of the said clamping devices consisting ofa clamping screw extending through the side of the collar, a bearing member in which the collar is pivotally mounted, said bearing member being made in the form of a segment with an open portion for the admission of the said clamping screw, and a. yoke in which the segmental bearing member is pivotally mounted.

7. In a device of the character described having means for measuring the deformation of a specimen, a clamping member having a gimbal joint embodied therein for embracing the specimen, and said gimbal joint composed of segmental members having open spaces for the admission of the speci: men from the side of the gimbal joint.

8. In a device of the character described having means for measuring the deformation of a specimen, a clamp-ing member having a gimbal joint embodied therein for engaging the specimen, a cheek plate carried by one of the-members of the gimbal joint and means for yieldingly holding the cheek plate against the members of the gimbal joint to hold them in alinement.

9. In a device of the character described, a clamping member consisting of a yoke, a bearing member pivotally mounted in the yoke, a collar pivotally mounted in the bearing member, a plate loosely mounted upon the side of one of said members and springs for yieldingly holding said plate against the several parts of the clamping member tending to hold said parts in alinement.

10. In a device of the character described having means for measuring the deformation of a specimen, a clamping member having a gimbal joint embodied therein for embracing the specimen, said gimbal joint composed of segmental members having open spaces in the sides thereof for the admission of the specimen from one side thereof, a check late yieldingly held against the face of t e gimbal joint, and said check plate having an open space formed therein corresponding to the open spaces of the members of the gimbal joint.

11. An extensometer comprising a frame, a clampin member secured in the frame, an arm plvotally mounted in said frame, a clamping member formed upon said arm, a spring acting against said arm to eliminate the lost motion in the clamping members, a removable locking device to hold the arm against the action of the spring, a micrometer secured in the frame adapted to be operated by the said arm and a stop mounted in the frame to limit the movement of the arm in the direction of the micrometer.

12. An extensometer comprising a frame having side plates, cross-pieces connecting the side plates, a clamping member secured in the frame, an arm pivotally mounted in the frame, a clamping member formed upon one end of said arm, a micrometer operated by the opposite end of said arm, a gimbal joint embodied in each of the said clamping members and means for securing a specimen in the gimbal joints.

In testimony whereof I afiix my signature in presence of two witnesses.

FERDINAND F. METZGER.

Witnesses:

ANNA C. THOMPSON, JOHN L. MAURER. 

